Success of Counterattack in Helmand Is Seen as Critical to Preserving Kabul's Hold in South

SANGIN, Afghanistan—Government forces are stepping up a counterattack against the Taliban after stumbling in their efforts to retake territory seen as critical to preserving Kabul's hold in the country's south.

A resurgent Taliban last month amassed hundreds of fighters in northern parts of Helmand province—a hotbed in the long-standing insurgency against Afghanistan's central government and the focus of President Barack Obama's...